Sleep loss is prevalent in humans and sleepiness contributes to increased accident rates. Additionally, sleepiness impacts cognitive function. Students that do not get enough sleep typically have lower grades than students that are not sleepy. The present proposal seeks to understand the mechanisms underlying cognitive dysfunction due to sleepiness. The first aim will study the role of adenosine during sleep loss and its impact on hippocampal function. The sleep of rats will be fragmented prior to learning a hippocampal dependent task so that training occurs while the rat is sleepy. Rats will be tested in either a one day water maze task or the social transmission of food preference task, a naturalistic memory task that is also hippocampal dependent. Some rats will have an adenosine antagonist dialyzed into the basal forebrain during sleep fragmentation. Alternatively, non-sleep disrupted rats will also be tested in which some will have an adenosine agonist dialyzed into the basal forebrain. A sub-aim will explore c-Fos activation in the hippocampus in the above described groups. A second aim of this proposal explores the effects of sleep fragmentation on adolescent and young adult rats. Young rats will undergo sleep fragmentation for 24 hours before testing in the water maze. Locomotor activity will also be measured following sleep fragmentation. This proposal hypothesizes a novel mechanism to explain why forming new memories while sleepy is difficult. This could provide powerful insight in the management of information processing in professionals that are routinely sleep deprived. The establishment of a precise neuro-mechanism could lead to more effective pharmacological manipulations. Additionally, the formation of new memories is especially important for the student population which is routinely sleep deprived. The use of a sleep fragmentation model more accurately models a typical reason for sleepiness in adolescents (e.g. interruption of sleep seen in sleep disordered breathing) as opposed to more typically used sleep loss models in rodents (e.g. gentle handling total sleep deprivation or small platform REM sleep deprivation). Understanding differential impacts of sleep loss on cognition in adolescents is important for the management of sleepy school children. PUBLIC HEALTH RELEVANCE: This project will aid in the understanding of the role of sleepiness in information processing. This is especially important for professionals that are routinely sleep deprived (e.g. medical staff, soldiers, first responders, students, etc.) but yet still need high cognitive performance.